Much of the research on the potential health benefits of alcohol has been done on men, and it is still not clear exactly why moderate amounts of wine seems to be good for heart health.
The Swedish research team studied 102 women under the age of 75, all of whom had survived a heart attack or heart surgery for blocked arteries. All participants were asked to record their alcohol intake for one week after a year..
And after at least a year, a heart tracing (ECG) was taken over 24 hours during routine activities in all the participants, to test heart rate variability or HRV.
HRV measures the changes in time intervals between the beats of the heart. Decreased variability has been associated with an increased risk of heart disease and death.
HRV was highest in women who drank 5 or more grams of alcohol a day, equivalent to more than half a standard unit, and lowest in those who drank no alcohol at all.
But further analysis showed that the type of alcohol consumed was important.
HRV was highest among women who drank wine, even after taking account of other influential factors, such as age, weight, and smoking habit. Beer and spirits had little impact on HRV.
The favourable effects on HRV may be one of the reasons why wine protects heart health, suggest the authors.